Answer

Yes, your computer has the file SULFNBK.EXE. (That is, if you have a Windows 95/98/ME operating system) It's a legitimate system file under those operating systems. It is not a virus!

Someone thought it would be cute to start this rumor floating about, just to see how many people would delete this file from their system. The good news is, it's not an important file, and most people who delete it will probably never know the difference. But if you have deleted it, it wouldn't hurt to restore the file.